Combine harvesters are becoming increasingly large and with ever wider cutting tables to enable a field to be threshed in an effective manner. The cutting table is, in itself, essentially wider than the actual harvester. During threshing, crop residues, such as chaff and straw, are generated. Unless the straw is to be collected, it is usually chopped into small pieces in a straw chopper, before it and the chaff are distributed on the field to help provide nutrient for forthcoming crops. For a variety of reasons, it is desirable to spread the crop residues behind the combine harvester and to the sides, as evenly as possible over a region essentially corresponding to the width of the cutting table. As the cutting tables become wider, it becomes increasingly difficult to spread over the whole of the intended width. The straw chopper generates in the chopping kinetic energy, which is utilized to spread the residues over the field, and this energy is sufficient for a width of about 8-9 m. When the cutting tables extend beyond 9 m, this kinetic energy is no longer sufficient.
By arranging fans downstream of the straw chopper, it is possible to handle and spread a larger quantity of crop residues and to do so over the larger width. EP 1 031 273 shows a combine harvester of the above-described type, which has fans for spreading the crop residues. In this solution, the outlet of the straw chopper is in the same plane as the inlets of the fans so as not to lose kinetic energy from the straw chopper. One problem with this solution is that chopped straw can be forced back from the fans to the straw chopper and thus prevent chopped straw from being blown out. In order to avoid this, large-diameter fans have therefore been provided to prevent chopped straw from being blown back into the chopper. Only half the width of the fan can thus be utilized and, in principle, the fans therefore need to be twice as wide. With twice as wide fans, the equipment becomes not only more cumbersome, but also dearer and more complex.
The object of the invention is therefore to provide a straw chopper having a feed-out device to enable straw to be spread at least over a width of about 9 m, but which, at least in part, is not afflicted by the above-stated problems.